TACOMA, Wash. — David Purchase, a Tacoma man who started one of the nation’s first needle exchanges to prevent HIV-AIDS among drug users, died Monday. He was 73.

The needle exchange Mr. Purchase started in 1988 in downtown Tacoma was quickly copied across the country, leading his friends and associates to call him a public health hero. All he wanted to do was prevent the spread of HIV-AIDS among drug users.

‘‘When he began talking about the needle exchange, his sense of social justice, Dave didn’t have a neutral gear or a reverse gear,’’ said Lyle Quasim, a friend since 1970. ‘‘Dave only had forward gears.’’

Mr. Purchase went on to found the North American Syringe Exchange and the Point Defiance AIDS Project and was instrumental in programs as far away as Australia and Italy.

‘‘He was the instigator, and everyone else was a supporting actor,’’ said Terry Reid, who worked with Mr. Purchase at substance-abuse programs.

‘‘He was a lovable, determined man, but he told [Congress], ‘You’re letting people die’ by not supporting the effort,’’ said Dennis Flannigan, a friend since high school. ‘‘He challenged authority in such an articulate, measured way, you could not defeat his logic.’’